This invnetion relates to maleimide/epoxy resin blends. In a specific aspect, the invention relates to the preparation of polymaleimide/epoxy resin blends having good high-temperature properties.
Maleimide resins are thermosettable materials useful in high-temperature electrical and structural applications. Cured bismaleimide resins have good properties for high-temperature applications. However, bismaleimides are expensive relative to other resins such as epoxy resins, and have been found difficult to process in electrical and composities applications. Therefore, bismaleimide resins have been blended with epoxy resins to improve processing characteristics and to lower costs.
It is known that careful selectin of the curing agent added to bismaleimide/epoxy blends is necessary, as the nature of the curing agent will have an effect on the properties of both the uncured and cured blends. For example, it is important in preparing electrical laminates for circuit boards to use a resin formulation which can be partially-cured to form a stable prepreg which does not further cure or gel prior to fabrication of the prepreg into a laminate, but which cures rapidly once the laminate is exposed to cure temperatures. Furthermore, it is important that the cured blend exhibit good high-temperature properties, including a high glass transition temperature, which is dependent to some extent on the maleimide/epoxy blend curing.
It is therefore an object of the invention to provide maleimide/epoxy compositions having suitable thermal properties and process stability for electrical and structural applications.